I saw this film at the Toronto International Film Festival in September, and every time I’ve seen its star, Nicole Kidman, since then, I think: “Thank God she’s OK.”

At the Golden Globes, in interviews and on red carpets, the 51-year-old actor remains poised and glamorous. But as the LAPD’s Erin Bell in Destroyer, she’s a mess. The opening shot shows her bloodshot eyes, and hair that might be dusty or greying or coked or some combination of those things. And while Kidman is svelte, Erin could only be called junkie-skinny. Any more burnt-out and she wouldn’t be working homicide – it’d be working her.

Destroyer is the latest from director Karyn Kusama, who specializes in strong, often conflicted female characters. Between stints in television, she has delivered Jennifer’s Body, about a possessed cheerleader; the science-fiction drama Aeon Flux, starring Charlize Theron; and 2000’s Girlfight, a first film both for Kusama and lead actor Michelle Rodriguez.

In Destroyer’s opening scene, Erin happens upon a John Doe murder victim clutching a dye-spattered banknote. She clearly knows more about this guy than she’s letting on to her bewildered partner, coworkers and superiors. Visiting a friendly face in the FBI, she tells him simply: “Silas is back.”

What follows is an Odyssean journey, as Erin aims to track down the mysterious Silas by visiting the various criminal wrecks he’s left in his wake, including the dying-of-cancer Toby (James Jordan) and the smooth-talking DiFranco (Bradley Whitford). Each encounter exacts a price, and we start to wonder whether there will be anything left of her, physically or metaphysically, by the end of the film.

The story’s timeline is cleverly fractured, but some scenes show a decidedly less haggard Erin from what is clearly a few years back, when she and fellow cop Chris (Sebastian Stan) were undercover, trying to take down Silas (Toby Kebbell) and his gang, and possibly falling in love on the job. We also see Erin dealing in the here-and-now with daughter Shelby (Jade Pettyjohn), who seems determined to make even poorer life choices than her mom.

Between the past and its consequences, a crackling screenplay from Phil Hay and Matt Manfredi never ceases to remind us that life is all about free will and the choices we make. All of hers stem from the answer to one simple question, posed halfway through the film: “What if we don’t?”

Along the way we see some people who choose to play at being bank robbers, while others put on a white hat to play cops and robbers. One character chooses to play Russian roulette, giving over free will to the chance of an empty chamber. Even a brief snatch of a ballgame on a radio speaks to the theme: “He just missed it. He’d like that one back.” We’ve all had days like that. Erin’s had a lot of them.

All of this plays out over a brooding score of Theodore Shapiro that suggests whales playing string instruments, possibly while being whipped. And speaking of anguish, I couldn’t decide whether the slow drip of clues into Erin’s story felt more like an IV or an ancient water torture.

Kidman proves a worthwhile companion through this underworld, even though you would probably cross the street (and maybe even move to a different city) to avoid bumping into Erin more than once. That’s the skill and the strength of the actor’s performance. Whether you choose to follow her katabatic journey – well, as the film makes eminently clear, that’s your choice. But there are rewards to those who take the leap.